Vic police revisit old sex crimes

Rapists should be afraid - a new cold case team is out to solve 20 of Victoria's worst sex crimes of the past three decades using advances in forensic technology.

Police are confident they will be able to track down and charge offenders who terrorised women up to 30 years ago by trawling through more than 500 pieces of evidence for the tiniest clues.

The head of the sexual crimes squad, Inspector Paul Binyon, said the sexual assault cold case unit planned to re-examine almost 300 cases, with priority given to the worst 20 cases that involved abduction, aggravation and weapons.

A pilot program over the past few years has looked at 13 unsolved sex crimes and solved 10 - some of which are still going through the courts.

Insp Binyon believes police will uncover serial rapists, some of whom are likely to be in jail or to have committed other offences.

"With advancements in DNA technology, we think it's timely to start reviewing some of these old unsolved serious crimes," he told AAP.

"If people are living thinking that they've gone undetected all these years then we're going to have a rude message for you, that we're going to catch up with you and bring you before the courts.

"Rape's one of the most insidious crimes to be committed on another person, it's so personal and invasive, and the victims of those crimes deserve the right and have an expectation that we'll never stop looking for the perpetrators."

Insp Binyon said when some of the crimes were committed, DNA technology was "primitive" and didn't allow for a proper examination of evidence.

Forensic scientists would now pore over that evidence - which could include items from panties to a dressing gown taken from the rape scene - looking for fresh clues.

"We're confident that's going to identify further forensic evidence in DNA, fingerprints and other inquiries that we can then use to relaunch some of these unsolved investigations," he said.

The investigations would also re-examine witness statements and other evidence to bolster cases and get convictions, he said.

Chief Commissioner Ken Lay said the unit was concentrating on some very high-profile cases and he was confident they could be solved.

"They're very, very important to us. Some of these are very, very difficult cases with lots of violence, and we know that we've got evidence still in our possession," he told reporters.

"With new investigative techniques, with new forensic techniques, we can actually identify the offender and put them before the courts.

"So in the not-too-distant future you'll start seeing offences as far back as 20 and 25 years where we'll actually be charging offenders."